Rocket projectile



Oct. 31. 1 W. w. PAGET r 3,3493% ROCKET PROJECTILE Filed Dec. 1-3, 1965 2 Sheets-Sheet l m uni- Maw/V7016 my fl mqfles 2 ,4657" by r United States Patent 15 Claims. (a. 102-495 ABSTRACT OF THE DISCLOSURE A rocket projectile is launced by a firearm and contains solid rocket fuel for maintaining its velocity. The rocket nozzle is shifted forwardly during initial firing to open a greatly enlarged path of access for the ignition of the solid fuel, and then is shifted rearwardly to close this enlarged passage and permit escape of the combustion products of the solid fuel only through the nozzle. A special adjustment regulates the size of the nozzle. A guiding and sealing ring is disposed at the front of the casing so that the pressures inside and outside the casing will be substantially equal and the casing can be desirably thin. The fuel can be arranged in desirably shaped packets.

This invention relates to a projectile launched by a firearm, such as for example a rifle, a machinegun, a submachinegun, a cannon, a howitzer, etc.

It is known that a projectile is subject in the air to a resistance which depends upon its velocity, upon its designthat is to say, upon its shape-and upon the surface Which it presents to the air.

This air resistance considerably reduces the range of the projectile, and also has the effect of reducing the kinetic energy of the projectile progressively as the latter moves further away from the arm which has fired it. In other words, the projectile possesses a kinetic energy which is the weaker as it moves farther away from the arm, and this is expressed as a reduction in the impact energy that is to say, a decrease in the eflicacity of the projectile; this is a serious disadvantage. For instance it is known that, for example, even in the case of a particularly well designed small calibre projectile, such as a known projectile of 7.62 mm. calibre, more than half the kinetic energy is lost as a distance of approximately 400 meters.

It is also known that a high velocity of the projectile on leaving the gun can greatly increase the shooting accuracyat long range, since the trajectory is flatter and the flight duration is shorter; the result of this is to make an inaccurate estimate of the range less important.

Moreover, since combat generally takes place only at fairly long distances, in order for the projectiles still to have high kinetic energy at the moment of impact at long range, despite the losses through friction in the air, it is necessary for them to possess high kinetic energy initially.

In order to give a projectile high initial energy, the initial velocity at the muzzle of the arm must be increased; this can be achieved by increasing the charge of burning powder required to propel it; however, there exists for all arms a charge of powder which must not be exceeded at the risk of producing serious disadvantages. Thus, in the case of a lightweight rifle for example, this charge is mainly limited by the recoil, since too large a charge of powder must not be used unless one is prepared to accept an exaggerated recoil; hence, in order to increase the exit velocity from the arm, it is the general practice to reduce the weight of the projectile, but another disadvantage is then encountered, because a lightweight projectile loses velocity more rapidly than a heavier projectile of the same calibre.

The principal object of the present invention is to 3,349,738 Patented Oct. 31, 1967 equip a projectile launched by a firearm with an additional propulsion device which acts after exit from the arm so that the initial velocity and kinetic energy-i.e., at the muzzle of the arm-do not decrease along the trajectory as with the known projectile, but on the contrary increase, or at least remain approximately constant during at least a portion of the trajectory.

According to one essential feature, the additional propulsion device is constituted by a motor of the solid fuel rocket type capable of functioning at the commencement of the trajectory for a variable, but generally short, duration; in other words, the body of the projectile contains a solid fuel with high combustion velocity, which may be constituted by any known fuel which, when once ignited, burns and yields gases under pressure which are expelled by way of a calibrated exhaust nozzle located at the rear of the projectile.

According to another feature, the ignition of the solid fuel contained in the projectile is preferably produced by the combustion gases of the powder which launches the projectile when the latter is still in the bore of the arm. It is therefore clear that, in contradistinction to an actual rocket, in a projectile according to the invention the initial velocity and the direction are dictated during the travel through the bore, by a propulsive charge which is entirely separate from the fuel charge contained in the said projectile.

It is further provided to make the throat section of the nozzle through which the gases pass exactly proportionate of the combustion surface of the fuel, with the object of controlling the combustion pressure of the fuel and hence its combustion velocity.

According to a further feature, the correct ignition of the fuel contained in the projectile is effected by providing in the projectile, in addition to the nozzle, at least one additional conduit which temporarily permits passage of the gases originating from the combustion of the propulsive charge; this channel, which is open during the period of acceleration, is closed as soon as the projectile leaves the muzzle of the arm.

In one embodiment, the additional conduit is of annular conformation and surrounds the body of the nozzle to issue behind a plate provided with passage orifices, formed for example by free spaces between radial arms and giving access to the rear face of the solid fuel, during the acceleration period, blockage of the channel being obtained by the plate coming into abutment against a shoulder around the said body of the nozzle, th-us constraining the combustion gases of the fuel to exit through the nozzle.

In another embodiment. two longitudinal conduits are provided placed laterally to the body of the nozzle and terminating behind a plate integral with the said body, in a chamber behind the solid fuel, blockage of the conduits being effected by the said plate coming into abutment against a shoulder around the nozzle.

According to another embodiment, the body of the projectile containing the solid fuel is closed at the rear by a plug in the form of a cup of which the base is pierced with orifices closed by valves subject to a plate spring maintained by a disc carrying the nozzle screwed into the cup.

The additional propulsion device according to the invention may be applied to any projectilesuch for example as an anti-tank projectile or shell of normal weight; the additional thrust provided by the rocket motor may be chosen to augment the velocity of the projectile after the latter has left the bore of thearm; now, since the kinetic energy is a function of the square of the velocity, an increase in the velocity during the trajectory gives the projectile a greatly increased kinetic energy, which may actually be sufliciently high to produce melting of a quantity of steel equal to several times the weight of the projectile, and thereby to render the use of armour difficult if not impossible, as its thickness would have to be too great in order to provide adequate protection.

Another equally important application of the invention is to a small calibre projectile such as a rifle or machinegun bullet or the like.

For a projectile to strike with reasonable efiicacity a target located at a certain range, it is necessary for it to possess a given kinetic energy at the moment of impact.

Hitherto, in order that the impact energy shall be sufficient, it is possible to give a small calibre projectile greater weight or a higher initial velocity; this produces the disadvantages already mentioned.

On the contrary, since by virtue of the additional propulsion device according to the invention the velocity at the place of impact can be maintained equal to the velocity on exit from the muzzle, it is possible to reduce the weight of the projectile and the charge for launching it; in other words, the device according to the invention makes it possible, for ordinary ranges, to produce a cartridge having, for example, approximately half the weight of a normal cartridge giving the same kinetic energy on impact. This has the advantage of greatly reducing the recoil, which facilitates the firing precision of lightweight or medium weight automatic arms.

Specific embodiments of the invention will now be described by way of example, with reference to the accompanying drawings, in which:

FIGURE 1 is an enlarged view in longitudinal axial section of a small calibre projectile constructed according to the invention.

FIGURE 2 is an enlarged view in longitudinal axial section of another embodiment of a small calibre projectile showing a nozzle with a hole plate forming a valve, and FIGURE 3 is a view in elevation of the front end of the nozzle.

FIGURE 4 is a view in longitudinal axial section of a projectile of larger calibre, and FIGURE 5 is a section view taken along the line VV of FIGURE 4.

FIGURE 6 is a view in longitudinal axial section of a large calibre projectile, and FIGURE 7 is a sectional view taken along the line VIIVII of FIGURE 6.

FIGURE 8 is a view in longitudinal axial section of another embodiment of a large calibre projectile.

FIGURE 1 clearly shows a projectile comprising a metallic casing 1, at the front of which a core 2, of lead for example, is placed; depending upon the object to be attained, this core may of course be of another material, such as steel. The casing 1 also contains the solid fuel 3 of any known nature, the rear of which possesses a cavity 5 having the form of a portion of a sphere, for example; this cavity is provided to give a suitable combustion surface. The projectile is closed by the body 4, in which the nozzle 4a is made. This body 4 is maintained in position by the sleeve 6. On firing, the burning gases originating from the combustion of the launching charge ignite the solid fuel 3 of the projectile, which is still in the bore of the gun. The fuel commences to burn, and the gases which originate from this combustion exit through the nozzle 4a at a pressure slightly greater than the pressure in the bore. As soon as the projectile has left the muzzle of the arm, it is subject to the thrust of the gases during the combustion of the fuel 3, which has a duration of approximately 0.3 to 0.5 second. It should be observed that the duration-that is to say, the velocity-of combustion depends upon the combustion pressure, which in turn depends upon the cross-section of the passage at the throat position of the nozzle. By adjusting the said crosssection, therefore, it is possible to adjust the duration of the thrust.

A second embodiment is illustrated in FIGURE 2, which shows a projectile of which the metallic casing 8 again contains a metallic core 9 and a solid fuel 10. In this case, the body 11 in which the nozzle 11a is made is secured against the rear of the fuel; this body is provided in front with a plate 12 which, as FIGURE 3 shows, has radial arms 13 for centering in the casing 8; hollow spaces 14 are made between these arms. Around the body 11 of the nozzle 11a there exists an additional conduit 15 of cylindrical form. In this embodiment, during the acceleration phase of the projectile in the arm, the combustion gases of the launching charge maintain the body of the nozzle 11a against the fuel 10, which they ignite at its periphery by passing through the cylindrical conduit 15 and the holes or cavities 14 between the arms 13.

When the projectile leaves the bore of the arm, it is no longer subject to the pressure of the launching gases; at that moment the solid fuel 10 and the gases produced by its combustion tend at first to exit by passing through the spaces 14 and through the annular conduit 15, but simultaneously they exert a thrust upon the plate 12, which is urged towards the rear. The latter thus performs the function of a valve, since it comes into abutment against the sealing shoulder 16 around the body of the nozzle; this constrains the burnt gases originating from the combustion of the fuel 10 to exit solely through the nozzle 11a; in this way the combustion pressure and the combustion velocity are then controlled by the passage cross-section of the nozzle. It is also possible to fill the annular conduit 15 with a compound performing the function of a primer and serving to maintain the nozzle 11 in position against the fuel 10, at a distance from the sealing shoulder 16, until the moment of ignition of the launching charge; this primer also serves to achieve good ignition of the fuel 10 through the hollow spaces 14. The primer, however, is not shown in the drawings, so as to avoid concentration of lines therein. The compound used as primer must have an ignition temperature below that of the fuel 10 in order to ensure that, in the event of premature firing, the projectile will have left the arm before the solid fuel explodes.

FIGURE 4 shows an embodiment of the projectile of larger calibre for a rifled arm; this projectile is constituted by a hollow body 17 containing the solid fuel 18, The plug 19 is screwed into the base of the projectile and possesses a central cavity 19a in which the body 20 provided with the nozzle 20a is housed; this body is maintained in position by the two diametrally opposite round-head pins 21 so long as the projectile is in the bore. The combustion gases of the launching or firing charge pass through the longitudinal conduits 20d provided diametrically opposite laterally of the body of the nozzle and continuing as far as the rear of the plate 20b which terminates in front the body 20 containing the nozzle 20a. These conduits 20d issue into the channel 20c which communicates with the rear face 18a of the fuel 18 so that the combustion gases of the firing charge are made to ignite the said rear face 18a. The plate 20b has a diameter slightly greater than that of the central cavity 19a housing the body 20. As soon as the projectile leaves the muzzle of the arm, the pins 21 are rejected by the action of centrifugal force, and the combustion gases of the fuel 18 urge the body 20 towards the rear so that the plate 20b comes into abutment against the shoulder 1% formed by the central cavity 19a; thus the channels 20d are closed and the combustion gases are then constrained to exit solely through the nozzle 20a; this adjusts the combustion pressure, and hence the thrust, to the value depending upon the calibrated section of the nozzle.

FIGURES 6 and 7 illustrate a projectile according to the invention, specially devised for piercing armour for instance, a piercing or antitank shell. In this case, the shell is constituted by a casing 22 containing the solid fuel 23, which assumes the form of a cylinder resting upon the ring 23b and having a longitudinal central cavity 23a. A metallic head 24 is screwed onto the front of the casing 22 and has a ring 25 to guide and seal the projectile in the bore; a similar ring 26 is also provided at the rear. The rings 25 and 26 are in two parts, as

FIGURE 7 clearly shows, and become separated from the projectile after the latter has left the bore of the arm. Orifices 26a are provided in the ring 26 only, in order to make the space around the casing 22 communicate with the bore, so that the same pressure is established inside and outside the projectile; this makes it possible to keep the casing 22 thin. A highly elongated cone 27, partly shown, is secured to the head 24; this is necessary at the high velocities involved. This cone may be, for example, of a plastics material, possibly stiffened by glass fibres; the front end or summit of the cone, not shown, is preferably constituted by a tip of a sintered alloy of tungsten and molybdenum, in view of the intense heat which is produced at this point of origin on the shock wave. At its rear end, the casing has a flange 22a for passage of the body 28, in which the nozzle 280 is made. The body 28 which is terminated at the front by the plate 28a is maintained by the conical pin 26b provided on the interior face of the half-rings 26, which occupy the holes 28b located diametrally in the flange 22a and in the said body 28. Laterally of the body 28, two longitudinal conduits 28 are made which continue as far as the rear of the plate 28a and issue into the chamber 28d which communicates, through the channel 28g, with the rear of the central cavity 23a. The propulsion gases emitted upon the launching of the projectile pass through the conduits 28 the chamber 28d, the channel 28g and arrive in the central cavity 23a, where they ignite the interior of the solid fuel 23, the base of which cannot burn immediately since it is protected by the ring 23]). A rod 29 passes through the head 24 and the longitudinal cavity 23a, so that its slightly tapered rear end 29a is located in the axis of the nozzle 28c; in front, this rod 29 has a screwthreaded portion 2% upon which a cap 290 is screwed by a greater or lesser amount in order to adjust the length of the rod; the pressure screw 30 permits the device to be fixed at the chosen length. According to this length, which is adjusted before firing the projectile, the tapered end 29a enters the nozzle 28c by a variable distance and reduces the passage cross-section at the throat of the nozzle to a variable extent. In this way the combustion pressure of the solid fuel 23 is modified so that the duration of combustion is also modified; it is possible to adjust this duration so that it corresponds to the time required by the projectile to travel the trajectory between the muzzle of the arm and impact.

When the gases produced by the combustion of the fuel 23 exit through the nozzle 28c, their thrust acts upon the projectile to maintain its initial velocity, or even to increase the latter, until a chosen moment, even until impact. It should be observed that, as soon as the projectile has left the bore of the arm, the combustion gases of the fuel 23 urge the plate 28a of the nozzle against the shoulder 22]) of the flange 22a so that they are able to exit only through the nozzle 280.

The solid fuel 23 is of course subject to a strong compression during the acceleration in the bore of the arm, and it must therefore possess a high compressive strength; it may be constituted, for example, by a mixture of powdered aluminum, ammonium or potassium perchlorate, and an epoxy resin, possibly with a strong material such as glass fibre.

FIGURE 8 also shows, in part, another anti-tank shell constructed according tothe invention. This shell comprises, as in the case of a known shell, a nose, not shown, having a metallic core 30 provided with a guiding and sealing ring 30a which maintains the pressure outside the casing equal to the pressure inside when the projectile is in the bore. The casing 31 is screwed onto the core 30 and is thicker in front than at the rear of the projectile, since it is required to withstand the thrust of the parts located at the rear; this casing must also be sufficiently thick to withstand the pressure of the gases when the ring 30a has already left the bore of the arm; it contains the solid fuel of known type, arranged in a plurality of packets such as 31a possessing a central cavity 31b and each supported by a dome such as 32. Each dome 32 which is of steel, has a cylindrical external part 320! constituting a suitable surface for the application of an epoxy adhesive in order to form a connection capable of transmitting the acceleration of the said dome and of the fuel 31a to the external casing 31, and a tubular internal part 320, resembling a chimney, which maintains the solid fuel during the acceleration and prevents it from burning from the center. The end 3212 is a portion of a spherical surface, so that, due to the effect of the very great acceleration in the arm, the fuel produces a uniform force in the dome. The packets of solid fuel are separated from one another by a passage-way such as 32d; they each commence burning from the free anterior face 322; from which the combustion proceeds and occurs over a surface which remains constant and approximately spherical; for a constant combustion pressure, the combustion velocity is uniform. The plug 33, hollow in the center and continued by the cuplike cylindrical part 34, is screwed onto the rear of the casing 31; the base of the said cup is pierced with orifices 35 which can be contacted by the closure valves 36 which are subject to a conical plate spring 37 maintained by the disc 38 with flange 38a which is screwed into the cup 34; this disc 38 is continued to form the nozzle 39. The volume of the central cavity determined by the part 320 is kept small, in conformity with the passage cross-section towards the nozzle, in order to keep small the quantity of gas which must flow through the orifices 35 to equalise the internal and external pressures. In the bore of the gun, the projectile is subject to an extremely powerful accelerational thrust; since the spring 37 is not sufficiently powerful to bear upon the valves 36 at that time, the orifices 35 are not closed during this travel in the bore, and the combustion gases of the packets 31a exit through the said orifices 35 which have remained open; as soon as the projectile has left the bore, the spring 37 bears upon the valve 36, which closes the orifices 35, and the gases are then constrained to exit through the nozzle 39. The rocket motor functions and its thrust maintains or increases the velocity of the projectile possibly until impact.

The present invention is not limited to the exemplary embodiments which have just been described, but it also relates, generally speaking, to all projectiles launched by a firearm of any calibre, whether by a light or portable arm or a heavy arm.

What I claim is:

1. A rocket projectile launched by a firearm and having an additional propulsion device constituted by a solid fuel rocket motor housed in the projectile, a calibrated nozzle in the rear of the projectile for the escape of combustion gases of the solid fuel of the rocket, a centering sleeve disposed in the projectile, a solid body carried in centered relationship by said centering sleeve, said calibrated nozzle being disposed in said solid body, a transverse plate disposed in the rear of the projectile, said plate having holes therethrough, said centering sleeve having a shoulder thereon, means defining an additional conduit from the rear of the projectile into the vicinity of said transverse plate, said additional conduit being closed when said transverse plate abuts against said shoulder, and means defining a channel issuing at the rear of said solid fuel and communicating with said additional conduit.

2. A projectile as claimed in claim 1, said additional conduit being cylindrical in form and surrounding said nozzle.

3. A projectile as claimed in claim 1, and radial centering arms carried by said transverse plate and defining holes and constituting said means defining said channel.

4. A projectile as claimed in claim 1, and two longitudinal additional conduits located diametrically on the periphery of said nozzle.

5. A projectile as claimed in claim 1, and radial pins maintaining said nozzle in the forward position to keep said additional conduit open so long as the projectile is accelerating within the firearm.

6. A projectile as claimed in claim 5, in which said radial pins are adapted to be ejected by centrifugal force as soon as the projectile has left the muzzle.

7. A projectile as claimed in claim 5, and an annular guide ring carried by the rear of the projectile, said ring carrying said radial pins, said ring being in the form of a plurality of radially outwardly ejectable parts.

8. A projectile as claimed in claim 5, and a flange at the rear of the projectile through which said radial pins pass and in which said nozzle is housed.

9. A projectile as claimed in claim 5, and a sleeve screwed into the projectile and housing the nozzle and traversed by said radial pins.

10. A projectile as claimed in claim 1, and a primer having an ignition temperature substantially below that of said solid fuel, said primer being disposed in said additional conduit.

11. A rocket projectile launched by a firearm and having an additional propulsion device constituted by a solid fuel rocket motor housed in the projectile, a calibrated nozzle in the rear of the rojectile for the escape of combustion gases of the solid fuel of the rocket, a cup screwed into the rear of the projectile, a disc screwed into the cup, the disc being integral with said nozzle and defining channels in said cup, valve means for closing said channels, and spring means acting on said valve means to open said valve means when the projectile has left the firearm.

12. A projectile as claimed in claim 11, said spring means being at least one leaf spring.

13. A rocket projectile launched by a firearm and having an additional propulsion device constituted by a solid fuel rocket motor housed in the projectile, a calibrated nozzle in the rear of the projectile for the escape of combustion gases of the solid fuel of the rocket, means mounting the calibrated nozzle for forward and rearward movement relative to the projectile, means defining ignition passageways of substantially greater cross-sectional area in sum than the nozzle, and means movable with said nozzle to open said passageways in the forward position of said nozzle upon discharge of the firearm and to close said passageways upon burning of said solid fuel.

14. A rocket projectile launched by a firearm and comprising a solid core, a solid fuel rocket-type motor disposed behind said core, a calibrated nozzle in the rear of the projectile for the escape of combustion gases of the solid fuel of the rocket, an axial rod extending through the forward end of the projectile and through said core and said solid fuel and terminating in a tapered end located in the throat of said nozzle, and means on the forward end of said rod accessible from the forward end of the projectile to adjust the axial position of said rod thereby to alter the shape of the cross section of the nozzle.

15. A rocket projectile launched by a firearm and having an additional propulsion device constituted by a solid fuel rocket motor housed in the projectile, a calibrated nozzle in the rear of the projectile for the escape of combustion gases of the solid fuel of the rocket, said solid fuel being arranged in packets superposed in said projectile, there being passageways separating said packets from one another, and a housing for each of at least some of the packets of solid fuel, each housing having an external cylindrical portion and an internal tubular portion and a closed rear end between said cylindrical and tubular portions and being forwardly open, so that the solid fuel can burn only from its front surface, said closed ends and said front surfaces being substantially spherical and having substantially the same curvature.

References Cited UNITED STATES PATENTS 2,460,289 2/1949 Hickman 102-49 2,552,497 5/1951 Roach et al -242 2,762,193 9/1956 Johnson 10249 X 2,884,859 5/1959 Alexander et al. 10249 X 3,011,309 12/1961 Carter 10249 3,115,271 12/1963 Anderson et al. 10292.5 X 3,122,884 3/1964 Grover et al 60252 3,277,825 10/1966 Maillard 10249 FOREIGN PATENTS 976,483 11/ 1964 Great Britain.

BENJAMIN A. BORCHELT, Primary Examiner.

V. R. PENDEGRASS, Assistant Examiner. 

1. A ROCKET PROJECTILE LAUNCHED BY A FIREARM AND HAVING AN ADDITIONAL PROPULSION DEVICE CONSTITUTED BY SOLID FUEL ROCKET MOTOR HOUSED IN THE PROJECTILE, A CALIBRATED NOZZLE IN THE REAR OF THE PROJECTILE FOR THE ESCAPE OF COMBUSTION GASES OF THE SOLID FUEL OF THE ROCKET, A CENTERING SLEEVE DISPOSED IN THE PROJECTILE, A SOLID BODY CARRIED IN CENTERED RELATIONSHIP BY SAID CENTERING SLEEVE, SAID CALIBRATED NOZZLE BEING DISPOSED IN SAID SOLID BODY, A TRANSVERSE PLATE DISPOSED IN THE REAR OF THE PROJECTILE, SAID PLATE HAVING HOLES THERETHROUGH, SAID CENTERING SLEEVE HAVING A SHOULDER THEREON, MEANS DEFINING AN ADDITIONAL CONDUIT FROM THE REAR OF THE PROJECTILE INTO THE VICINITY OF SAID TRANSVERSE PLATE, SAID ADDITIONAL CONDUIT BEING CLOSED WHEN SAID TRANSVERSE PLATE ABUTS AGAINST SAID SHOULDER, AND MEANS DEFINING A CHANNEL ISSUING AT THE REAR OF SAID SOLID FUEL AND COMMUNICATING WITH SAID ADDITIONAL CONDUIT. 